In the Twin Cities, Monday night’s overnight low of 23 below was the coldest temperature in a decade and practically a generation. The National Weather Service called it “a historic and life-threatening cold outbreak.” Frostbite patients swamped hospital emergency rooms.

After Monday’s high of 12 below, a few degrees of consolation is in sight: Tuesday’s predicted Twin Cities high is expected to be near zero. But before the long slow climb toward zero begins, windchills in the early morning hours are once again expected to register at between 35 and 55 below across much of ­Minnesota and western Wisconsin.

Video (02:06): Looking for a way to keep warm and have fun?

The majority of Twin Cities metro school districts called off school for a second day Tuesday — elation for kids but pure panic for working parents left in another day-care lurch.

Many people heeded the advice to stay home like the kids: Minneapolis parking ramps were half full and ­traffic was sparse with many workers staying home or telecommuting.

“It’s amazing to me to see the city had literally shut down,” Kelly Hillier said of her easy commute into downtown Minneapolis. “I was amazed there was nobody on the road.”

Those braving the cold were wrapped to their eyeballs in scarves, hoods, hats and parkas. The trails around Lake Harriet were nearly deserted except for Patrick O’Brien, who ran around the lake while his wife stayed home with the kids. Feeling a little playful, he wore his Spider Man Halloween costume.

“It feels great, “ he said, even admitting he worked up a little bit of a sweat with all the layers.

Sun Country Airline pilot Torben Kiese, just back from Tampa, Fla., took a stroll across Lake Harriet Monday morning under blue skies.

“It’s pretty down there. It’s a different kind of pretty here,” Kiese said. “You have to be careful. That’s for sure. If you dress right, it’s OK. The view from the middle of the lake is fantastic.”

At the same time, the Minnesota Department of Health sustained a possible $1 million worth of damages and suspended all testing in its infectious disease and environmental laboratories after its heating system failed Monday, causing water and freezing damage to equipment.

Short-lived ‘warmth’ coming

The deep cold is simply an intensification of global weather patterns that brought us a chilly December. A distorted jet stream has sent polar air directly south scross the Great Plains, while Fairbanks, Alaska, recorded 19 degrees at midafternoon Monday.

Although Twin Cities temperatures are predicted to warm toward 30 this weekend, the “polar vortex” is already reforming and could put Minnesota back on ice next week, said National Weather Service meteorologist Rick Hiltbrand.

In other words, it’s still early ­January with more winter to come.

“To say we couldn’t have 25 below zero temperatures again this winter, I wouldn’t do that,” Hiltbrand said.

Day-care scramble

Minnesota Gov. Mark Dayton had closed all K-12 schools in the state on Monday because of the bitter cold, but he let individual districts make the call Tuesday. Most remained closed, but there was at least one exception — classes in Bemidji were slated to resume Tuesday. It’s rare for schools in Minnesota to close for back-to-back days because of bitter windchills. In 1994, Gov. Arne Carlson canceled classes statewide on Jan. 18. The next day, most school ­officials opted not to reopen.

On Monday, Education Commissioner Brenda Cassellius reiterated the desire to let local school officials make the call whether to resume classes on Tuesday. Shortly after she made that point, a slate of school closings was announced.

Video (00:39): Sub-zero surfing on Lake Superior

The closings caused panic for some working parents scrambling to find child care again.

Nurse Ryan Giacomini had ­Monday off so he could watch his 12- and 5-year-old sons, but said he’ll have to rely on family Tuesday. “I will probably lean on my dad who just retired,” said Giacomini of Roseville.

Even though finding last-minute child care can cause stress for ­parents, Giacomini said he doesn’t fault school officials.

“It’s dangerously cold to be standing at a bus stop. It doesn’t take long for those little ears and little fingers to get frostbite,” he said.

With school called off, parents and families seeking relief from the cold and cabin fever descended on Mall of America’s Nickelodeon Universe Monday for free rides.

That was a bonus for Yusuf Ahmed, who arrived with his four kids, learning soon after that school would be closed again Tuesday.

“I guess it will be another day at the mall,” he said. “It not fun for the adults.”

Frostbite victims

Chris Havens

Gallery: Bitter cold in Minnesota

Hennepin County Medical Center has already had far more severe cases of frostbite — those that require hospital admission —than it does in an entire normal winter, said Dr. Ryan Fey, medical co-director at the HCMC burn center. One winter might see 25 to 30 admissions, but New Year’s Eve alone brought 15, including 10 severe cases.

“The biggest thing is to stay inside if you’re able to, or if you’re out in the elements for any reason, make sure you have warm clothing, gloves on your hands and a hat on your head,” he said. “And absolutely avoid ­alcohol if you’re going to be outside.”

Regions Hospital has treated 14 people with frostbite and eight people with hypothermia over the past two days. Frostbite patients filled all eight ICU beds in its burn center.

Outdoor work on the Twin ­Cities’ two new sports stadiums — for the Vikings in Minneapolis and the Saints in St. Paul — was called off as well Monday and Tuesday due to the chill.

“Apparently it’s not only hard on equipment, it’s hard on people, too,” said Joe Campbell, a spokesman for St. Paul Mayor Chris Coleman.